Since a honeycomb structure is light in weight and excellent in mechanical properties, it has been widely used heretofore as an interior material, an exterior material or the like for structures used in various industrial fields including vehicles such as automobiles, aircrafts and ships and building construction. In addition, a synthetic resin honeycomb structure has also been employed as an impact absorbing part for automobiles or the like.
For example, Japanese Unexamined Patent Application Publication No. 2013-237242 (Patent literature 1) describes that a honeycomb structure that has both rigidity and impact absorbing property and that has excellent continuous moldability can be achieved by using a thermoplastic resin composition that is obtained by blending an ethylene-unsaturated carboxylic acid ester copolymer such as a glycidyl methacrylate-modified polyethylene copolymer with a polyamide such as nylon 6 to produce a honeycomb structure having a specific cell shape.
Since, however, conventional honeycomb structures are inadequate in water resistance, the mechanical properties of the honeycomb structures are degraded once water intrudes inside them, which raises a problem of limiting the usage thereof. In addition, there has been a need for expanding its applications by enhancing gas barrier property and heat resistance and by further enhancing the strength and the elastic modulus.